gnelson22 ,
Are you referring to the 737 "Classic"?
First, the 737 Classic should not use both packs on the ground except for heating. (The NG aircraft will freeze your socks off with both packs on in summer. It be much mo-bettuh.
)
The pack valves on the 737 are electronically controlled and pneumatically operated. The bleed air that these valves control is 400+ degrees. By "Freezing" I assume you mean sticking. I have heard of this happening on virtually all the pneumatic valves in the 737 as age, coking and wear take it's toll.
The side with the pack on will show 15-25 PSI depending on airport elevation. The side with no pack on should show 30 PSI - 1.2 PSI per 1000 feet above Sea Level. If it is showing less than the other side when both packs are off there is a leak in the manifold structure or through the inoperative pack valve (as you said, it's stuck partially open and some pressure is leaking out) Play with the ISOLATION VALVE. Isolating the two sides will point toward the side with the leak.
Hope this helps!
PT (The Banned One)
